I occasionally like to research common relationship questions on Google--a fact which may further incriminate me as a love junkie and extreme nerd. However, some of my favorite things to read are not from other self-proclaimed gurus, psychologists, or other old people, but from real people speaking from experience.
I came across this topic on an AnswerBag post: "How often should a boyfriend call you?" The answers are pretty funny and actually very informative.
Check it out here.
In my opinion, the answer to this question really depends on the seriousness of the relationship. If you're just dating a guy somewhat casually, a call once a day or every other day should suffice. For a "real" relationship, he should definitely make at least one attempt a day, if not 2-3. Women should make an effort, too; it's up to both people to show their interest. Whether you're a guy or a girl, aim to make at least one attempt to contact your partner each and every day, if possible.
Of course, some people just don't like to talk that much. Although it's not something I come across often, some people prefer to limit their contact with their partner to as little as once every few days or something. I'm not for or against that, but remember to choose someone who has similar communication needs to you. If you like to talk three times a day and your partner likes to give a quick call a couple times a week, that's not gonna work and it never will.
I want to stress gender-neutral language here so that you LGBTers know that I'm talking to YOU, too. Just because you're both guys or both girls doesn't mean that you both are going to communicate the same way. Stick with the once-a-day rule and regardless of how your relationship is, never fully depend on someone else to show interest while you just sit back. Like the old folks say, it takes two to tango. Never forget that.